#include<iostream>
#include<vector>
using namespace std;


int maximalRectangle(vector<vector<char>>& matrix) {
    int m = matrix.size();
    if (m == 0) {
        return 0;
    }
    int n = matrix[0].size();
    vector<vector<int>> left(m, vector<int>(n, 0));

    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (matrix[i][j] == '1') {
                left[i][j] = (j == 0 ? 0 : left[i][j - 1]) + 1;
            }
        }
    }

    int ret = 0;
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (matrix[i][j] == '0') {
                continue;
            }
            int width = left[i][j];
            int area = width;
            for (int k = i - 1; k >= 0; k--) {
                width = min(width, left[k][j]);
                area = max(area, (i - k + 1) * width);
            }
            ret = max(ret, area);
        }
    }
    return ret;
}

int main()
{
    vector<vector<char>> matrix = { {'1', '0', '1', '0', '0'}, {'1', '0', '1', '1', '1'}, {'1', '1', '1', '1', '1'}, {'1', '0', '0', '1', '0'} };
    cout << maximalRectangle(matrix) << endl;
    return 0;
}